Cockpit had already said last week that it was ready to stage walkouts over its demands for better provisions for pilots nearing retirement age.

"At the same time, Cockpit has said it is prepared to reach an agreement at any time to avert the strikes," it said.

A new round of talks were scheduled to be held on Thursday and "should an agreement be reached, the strike will naturally not take place," the union said.

Cockpit already grounded thousands of flights of the parent company Lufthansa during three days of strikes in March and April in pursuit of its demands, costing the airline around 60 million euros ($79 million).

Lufthansa said it "very much regrets this strike announcement and particularly the inconvenience it will cause Germanwings customers".

The airline said it was "looking into what impact the strikes will have on the talks with the union".

It could not yet say how exactly many flights would be affected, Lufthansa added.